A recent study has shown that the body mass index (BMI) is insufficient to detect obesity in people with chronic kidney disease (CKD). According to the data, only 38.9 percent of the patients assessed would be classified as obese if only this parameter were applied, whereas more than 63.5 percent met obesity criteria when evaluating waist circumference or the waist-to-height ratio.
The "Oberce" project, which will be unveiled at the 56th Congress of the Spanish Society of Nephrology (SEN), in Murcia, examined 2,036 adults with CKD treated in Nephrology outpatient clinics at 20 Spanish hospitals between February and August 2025. The analysis detected that 558 people, 27.4 percent of the sample, had "hidden obesity," meaning their BMI was in the normal range, but other measurements showed excess visceral fat.
The study’s leads, Drs. Clara García Carro and María José Soler, have warned that not diagnosing obesity means overlooking the appropriateness of intervening on it, a limitation especially important in a context in which new pharmacological options are already available to treat obesity and CKD together.
Both diseases share pathophysiological mechanisms that can be mutually reinforced, while excess adipose tissue contributes to deterioration of kidney function and increases cardiovascular and metabolic risk.
The study also reviewed the medication the patients were taking and found that 24.1 percent of those who met criteria for clinical obesity were receiving GLP-1 receptor agonists. In this group, the presence of hypertension, diabetes, and heart failure was more common.
Likewise, the analysis highlighted differences between sexes, with clinical obesity more frequently in women. Women with obesity showed more impaired kidney function than men, with an estimated glomerular filtration rate of 36 versus 40 ml/min/1.73 m1, and they received ACEi/ARB II, SGLT2 inhibitors, and GLP-1 agonists less often.
The president of the SEN, Emilio Sánchez, has emphasized "the need to go beyond the BMI to diagnose obesity in people with CKD and to continue to delve into the close relationship between these two conditions". Along these lines, he has advocated for incorporating complementary measurement methods that make it possible to detect cases that go unnoticed.
CKD, a growing public health challenge
Chronic kidney disease has established itself as a major public health problem and continues to rise both globally and in Spain, where it is estimated that it already affects 15 percent of the population—that is, close to seven million people, including those who have not yet been diagnosed.
In our country, the prevalence and mortality of people undergoing renal replacement therapy (RRT)—patients on dialysis or with a kidney transplant in order to continue living—have increased by more than 30 percent over the last ten years. Currently, more than 68,400 people with CKD are in RRT and, each year, more than 7,000 new patients are added to dialysis and transplant programs, of whom 25 percent reach this situation due to diabetes.
"If CKD maintains its current rate of growth, and we do not move forward with the measures and actions that we have been calling for—such as those focused on the prevention and screening of kidney health in the population at risk—by the year 2040 one third of people over 65 years of age in Spain will have CKD and it will be the fifth leading cause of death in our country", Emilio Sánchez has warned.
Annual Congress of the Spanish Society of Nephrology
Around 1,300 nephrologists and specialists, both national and international, will gather from this Thursday until Saturday in Murcia at the annual meeting of the SEN. During these sessions, the management of kidney diseases will be addressed, with special attention to CKD, reviewing the most recent advances, new research lines, and pending challenges in order to optimize prevention, diagnosis and treatment, as well as patients' quality of life.
Another key purpose of the Congress is to raise social and professional awareness of the magnitude and impact of CKD, highlighting its repercussions on the health and daily life of those who suffer from it, as well as the high burden it entails for the public health system.
The scientific program includes the latest developments in ERC and in the main areas of Nephrology, such as kidney transplantation, the various modalities of dialysis, glomerulopathies, hypertension and cardiovascular risk or vascular access, among other fields.
Innovations that are changing nephrological practice will also be presented, such as artificial intelligence, precision medicine and genetics, along with the development of new diagnostic and therapeutic tools and the arrival of new drugs.
Likewise, progress in dialysis, kidney transplantation and care for advanced ERC will be reviewed, as well as issues of particular interest such as the application of a gender perspective in acute kidney failure, menopause and reproductive history as a marker of cardiovascular and renal risk, the challenges of onconephrology, the relevance of personalized nutrition in ERC, living donation, new molecules with nephroprotective effect, aging and ERC, and anemia.
Other sessions will focus on the comprehensive support of the person with kidney disease, shared decision-making with patients, and interdisciplinary collaboration among healthcare professionals. The forum will make known the scientific output of nephrologists through 750 communications that compile the most recent studies and research on kidney disease carried out in Spain.